Data

Where do these data come from?

The data in this platform are from low- and medium-cost sensors (defined here as sensors that typically cost between $20 and $25,000) that have been deployed by a wide variety of stakeholders, including citizen scientists and community advocates, researchers, government agencies, and sensor manufacturers. Anyone can upload data onto the AQDC as long as the data are compatible with with the AQDC's basic quality characterization (e.g., the data use the AQDC's Date and Timestamp Guidelines and include meteorological data). The AQDC makes no guarantees about the quality, accuracy, and/or precision of the data uploaded by data providers.

What types of data are in this platform?

The AQDC currently has data on black carbon (BC), particulate matter (PM2.5 and PM10), ultrafine particles (UFP), carbon monoxide (CO), carbon dioxide (CO2), NOx, methane (CH4), and ozone (O3), as well as associated GIS and meteorological data (temperature, relative humidity, atmospheric pressure, and wind speed and direction).

What can you tell me about the quality of the data?

The AQDC cannot guarantee the quality, accuracy, and/or precision of the data uploaded by data providers, because anyone can upload data onto the AQDC as long as the data are compatible with the AQDC's basic quality characterizations (e.g., the data use the AQDC's Date and Timestamp Guidelines and include meteorological data). Users should evaluate the appropriate metadata before using any data, and direct questions about data quality to the data provider.

How can data be used?

The data on the AQDC and the AQDC itself are freely available for any use, such as analyses, maps, models, and reports as long as the data is used in accordance with the terms of service. Users should cite the original source(s) of the data they use and follow requirements from the applicable data licenses (CC0 or CCBy).

Because the AQDC cannot guarantee the quality, accuracy, and/or precision of the data uploaded by data providers, users should evaluate the appropriate metadata before using any data, and direct questions about data quality to the data provider.

When and how should I attribute data that I use or download from the platform?

Please cite the original source (the owner) of any data you use, in addition to the AQDC as the access point for the data. Attribution is required for all data designated by the provider as "CC-By." Data users should make every attempt to cite the original source of any data they use, even if the data is listed as "CC0."

Here is some suggested language for data attribution:

Single source: "The data were accessed from the AQDC [insert aqdc website] and originate from [XXX source/data owner]."

For multiple data sources (where logistically difficult to list every source): "These data were accessed from the AQDC and originate from multiple sources; see aqdatacommons.org for list of sources."

How are the data licensed?

Data are licensed either under CCBy or CC0 at the discretion of the data owners. Information about whether individual data sources are CCBy or CC0 is recorded in each data report.

Why might some data have limited spatial, temporal, or air pollutant coverage?

The AQDC is a platform for sharing data. It only features data that have been uploaded by data providers. If there is sparse spatial, temporal, or air pollutant coverage (e.g., you can only find data for one location, or no data collected at the time at one time, or no data for your pollutant of interest, etc.), it is because more comprehensive data have either not been collected or have not been uploaded to the AQDC.

Why might data contradict each other?

There are many reasons why data may contradict one another. For example, data collected at different times at the same location could accurately reflect changes in air quality over time. Different sensors can differ in their accuracy and/or precision, so measuring air quality at the same time and place with different sensors can yield different data. The AQDC makes no guarantees on data quality. Any questions about data quality should directed to the data provider.

Can I download the data?

We encourage users to use the data within the platform and take advantage of the platform's many features, such as the community and analytical tools, but the data can be downloaded.

How frequently are data updated?

Data are updated as data providers update them.

What should I do if I believe the data to be inaccurate?

If you believe data to be inaccurate, please fill out the contact form with relevant details.

How long are the data stored?

The data will be stored as long as the AQDC exists.

How do I know if my data are appropriate for the platform?

If you own air quality data for black carbon (BC), particulate matter (PM2.5 and PM10), ultrafine particles (UFP), carbon monoxide (CO), carbon dioxide (CO2), NOx, methane (CH4), and/or ozone (O3), as well as associated GIS and meteorological data (temperature, relative humidity, atmospheric pressure, and wind speed and direction) that were gathered via low- or medium-cost sensors, then it's highly likely your data are suitable for the platform. The AQDC does have some rules for data inclusion. For example, if you upload data where the latitude or longitude is out of range, your data will likely be excluded from the main data "store." Similarly, if you do not include humidity data in your measurements of particulate matter, your data might also be excluded, because PM measurements fluctuate based on humidity. A link to these rules, predefined by the ASW, can be found here.

Why can't I delete data?

In order to foster transparency and consistency and allow people to access data that have been used in publications, data must always remain available on the AQDC. If your data have changed or been updated following subsequent analysis, please feel free to upload your new dataset and archive your old version. Your archived version will still be available to users, but it will send a signal to data users that there is a more current version that should be used when conducting subsequent analysis.

How can I request a feature?

We value users' feedback on how to improve the AQDC's features and functionality. Please use our Github page to share your suggestions.